75من فضلك shdsndjdkskdjjsdjcjjsj
Shouldn't the answer be: (-1,4),(1,4),(2,4),(-2,4)
So two lines that are parallel will have the same slope, and to calculate the slope you have to use the formula 
CD:
.
JK: 
EF: 
GH:
(undefined)
In short, Lines CD and EF are parallel.
It's 48 because 23+48=71
So 71-48=23